San Francisco police officer arresting skateboarder: "I'll break your arm like a fckng twig."

In the video above, which is making the viral rounds: a San Francisco police officer who IDs himself as "Officer Schwab, (badge number) 2099" arrests a skateboarder identified as Zach Stow, after Stow calls the officer a "fckng dck." Over at metblogs SF, Richard Ault says the officer's understanding of SF skateboarding codes is wrong. An article about the incident is here at the SF Chronicle. My two cents, as someone who is neither a lawyer, nor a skateboarder: taunting a police officer by calling him a "fckng dck" is about as dumb as it gets, but that does not give the officer the right to threaten to break the guy's arms, or arrest him for -- what was it, in the end, failing to carry identification? In any case: viva la video camera. (thanks, Jacob Appelbaum)